Causes and consequences of invasions of aquatic ecosystems by non-native salmonids – SalmoInvade

In-situ experimentation
Ex-situ experimentation
Field monitoring
Meta-analyses
Questionnaires to stakeholders
Desktop survey
Meeting and transfer with stakeholders

Key results: (1) Non-native salmonid species, as well as non-native populations of native species, can have substantial negative ecological effects on native biodiversity (2) Domesticated non-native fish can to some degree be controlled by intensive fishing given their high vulnerability to angling (3) There are substantial differences in governance of salmonid stocking and transfer between and within the four countries, both in objectives, sectorial organization and levels of decision-making, as well as in trends and volume of salmonid stocking (4) The public awareness of non-native salmonids and their potential effects on biodiversity is low. However, citizens intuitively tend to prefer salmonid-friendly river environments (5) Studies on angling clubs in France and Germany show that potentially negative biological effects have little effect on local decisions to stock non-native salmonids. These practices are rather influenced by contextual factors which overall are more important than psychological factors.

Policy implications: (1) Monitoring, reporting and evaluation of stocking and transfer activities in all European jurisdictions are generally lacking and should be improved. (2) Stocking of non-native species and populations of salmonids should be avoided unless the practice follows strict guidelines to meet goals of native biodiversity conservation. (3) Local and regional authorities should be empowered to enforce regulations and to evaluate practices for salmonid stocking (4). Within the framework of international conservation agreements, strategies for salmonid conservation should be devised in accordance with the variation in public perception of native salmonids across European countries (5). Science – policy – public cooperation and dialogue is strongly encouraged to achieve more sustainable conservation practices for salmonids.

Involving French Partners - Peer-reviewed publications only:

Buoro M., Olden J.D. & Cucherousset J. 2016. Global Salmonidae introductions reveal stronger ecological effects of changing intraspecific compared to interspecific diversity. Ecology Letters. 19: 1363–1371. DOI : 10.1111/ele.12673.

Závorka, L., Koeck, B., Cucherousset, J., Brijs, J., Näslund, J., Aldvén, D., Höjesjö, J., Fleming, I. A. & Johnsson, J. I. 2017. Co-existence with non-native brook trout breaks down the integration of phenotypic traits in brown trout parr. Functional Ecology DOI: 10.1111/1365-2435.12862

Comte L., Cucherousset J. & Olden J.D. 2017. Global test of Eltonian niche conservatism of non-native freshwater fish species between their native and introduced ranges. Ecography 40: 384-392. doi: 10.1111/ecog.02007

Riepe, C., Fujitani, M., Cucherousset, J., Pagel, T., Buoro, M., Santoul, F., Lassus, R. & Arlinghaus, R. In press. What determines the behavioral intention of local-level fisheries managers to alter fish stocking practices in freshwater recreational fisheries of two European countries? Fisheries Research.

Aas Ø, Cucherousset J, Fleming IA, Wolter C, Höjesjö J, Buoro M, Santoul F, Johnsson JI, Hindar K & Arlinghaus R. Submitted. A comparison of governance of salmonid stocking in five North Atlantic jurisdictions indicates substantial variation in aquatic biodiversity conservation.

Zavorka L., Buoro M. and Cucherousset J. Submitted . The negative ecological impacts of a globally introduced species decrease with time since introduction.

Millions of non-native fishes (both species and genotypes) are regularly released into the wild in Europe, either intentionally by stocking or non-intentionally by escapes from aquaculture. Non-native fishes can become invasive and constitute a continuous threat to biodiversity. Salmonids are an iconic fish family of great socio-economic and cultural importance in Europe. They are widely distributed in both marine, coastal and freshwater ecosystems, and they continue to be cultured and released in large numbers into the wild. Often non-native genotypes are transferred across catchments creating a ongoing ecological and genetic burden on wild fish. Overall, salmonids constitute an excellent model system to study the causes and consequences of invasions using an integrated approach that combines ecological, evolutionary, fisheries biological and socio-economic approaches.
Our SalmoInvade proposal combines expertise from five research institutions/countries to study salmonid fishes as potentially invasive species/genotypes, and understand the psychological, economic and governance conditions and pathways by which humans relate to these fishes. Our objectives are (1) to understand the invasion potential of non-native salmonids in nature, including genetically modified and non-native genotypes, and their ecological and genetic impacts, (2) to reveal the biological and social mechanisms of establishment, and (3) to understand how the public and stakeholders in various European cultures conceptualize and rationalize biological invasions and their own engagement in the spread of non-natives in light of their perceptions about complex concepts such as biodiversity and biological invasions. In order to achieve our aims, we have designed studies :

1.to evaluate current releases of non-native salmonids in Europe and the social, economic and ecological mechanisms underlying their invasion potential,
2. to investigate the ecological and evolutionary impacts of biological invasions by salmonids,
3.to evaluate how salmonid invasions are perceived by the public and by key stakeholders.

Our project finally aims at providing well-informed, integrated recommendations for policy and management of salmonid invasions.
The project will be organized in four work packages (WPs) addressing the main objectives of the proposal. Each WP is divided into several tasks, each addressing a specific sub-objective of the WP. SalmoInvade will be coordinated by Professor Jörgen Johnsson at the University of Gothenburg. Prof. Johnsson will also lead WP1. WP2 will be jointly led by Dr. Kjetil Hindar at the Norwegian Institute for Nature Research (NINA) and Dr. Julien Cucherousset at University Paul Sabatier/CNRS, and WP3 will be led by Professor Robert Arlinghaus at the Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB) in Berlin, Germany. WP 4 will be coordinated by Jörgen Johnsson with contribution from all partners. Other project participants will take an active part in the project through their involvement in several WP and tasks. The strength of our proposal is the building of a strong interdisciplinary team that contributes complementary competences in genetics, ecological, human dimensions and environmental economics, revolving around the important model systems “salmonid species”. With our project we want to develop the foundation for sustainable development of salmonid fisheries in light of the societal desire to curtail their invasion potential.